Re: Layout-dependent feature subsetting

Skef wrote:
> With respect to layout features, IFT sits in the overall font stack at 
> the same level as a shaper. That is, you tell the "client-side IFT 
> subsystem" what you need using parameters analogous to how you tell 
> your shaper what you need.
>
> So in your case, it seems (and correct me if I'm wrong) that whatever 
> higher-level layout settings may be at issue, at some point you're 
> going to feed codepoints into your shaper with the rtla and/or rtlm 
> features active (or if you have a more custom shaper do something 
> equivalent, such that it will wind up digging around in the lookups 
> indicated by those tags). Therefore your overall system must be 
> "rtla/rtlm 'aware'" in at least that sense.

That makes sense. So the expectation is that the client will be passing 
all the discretionary layout features applied to the text, regardless of 
whether they have been applied by the user or by whatever process is 
handling text arrangement.

Would be a good idea to make some test cases around this for CJK and 
bidi related layout-dependent features.

J.


-- 

John Hudson
Tiro Typeworks Ltdwww.tiro.com

Tiro Typeworks is physically located on islands
in the Salish Sea, on the traditional territory
of the Snuneymuxw and Penelakut First Nations.

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